ADP1147-3.3

The ADP1147 is part of a family of High Efficiency Step-Down Switching Regulators. These regulators offer superior load and line transient response, a user defined current limit and an automatic power savings mode. The automatic power savings mode is used to maintain efficiency at lower output currents. The ADP1147 incorporates a constant off-time, current mode switching architecture to drive an external P-channel MOSFET at frequencies up to 250 kHz. Constant off-time switching generates a constant ripple current in the external inductor. This results in a wider input voltage operating range of 3.5 V* to 16 V, and a less complex circuit design.

A very low dropout voltage with excellent output regulation can be obtained by minimizing the dc resistance of the Inductor, the R_SENSE resistor, and the R_DS(ON) of the P-MOSFET. The power savings mode conserves power by reducing switching losses at lower output currents. When the output load current falls below the minimum required for the continuous mode the ADP1147 will automatically switch to the power savings mode. It will remain in this mode until the inductor requires additional current or the sleep mode is entered. In sleep mode with no load the standby power consumption of the device is reduced to 2.0 mW typical at V_IN = 10 V.